Flight control device, more particularly for fast aircraft



Aprif 23, 194i). P. E. KOSTER. 2,17,890

FLIGHT CONTROL DEVICE, MORE PARTICULARLY FOR FAST AIRCRAFT Filed April 2, v1938 2 Sheets-Sheet 1 April 23, 1940.

P. KOSTER FLIGHT CONTROLv DEVICE, MORE PARTICULARLY FOR FAST AIRCRAFT Filed April 2, 1938 2 Sheets-Sheet 2 Patented Apr. 23, 1940 mon'r CONTROL DEVICE, Moan PARTICU- LABLY FOR FAST amour-r Paul Eduard Ki'ister, Berlin-Siemensstadt, Germany, assignor. to Siemens Apparate und Maschinen Gesellschai't mit beschrankter Hattung, Berlin, Germany, a corporation of Germany ' Application April 2, 193a, Serial No. 199,125

' In GermanyApril 3, 1937 2Claims.

The present invention relates. to! a flight surveying instrument to be used more particularly for high speed airplanes and-comprising a device for indicating the side inclination. The side in- 5 clination is determined by a gyroscopic horizon as well as by a physical pendulum, for instance a ball level. Such a double indication of the side inclination has, besides the possibility of the mutual control, the advantage that the true side inclination of the airplane, which effectively exists, is known through the gyroscopic horizon, which is not subjected to accelerations of short duration and,accordingly, always remains in the ball level or another physical pendulum is no longer sumcient for maintaining a correct side inclination. The reason for this is thatevery slope error principally causes a side acceleration imtil a stationary slip condition has been attained. Low speed airplanes with high and sharp edged frames permit only of small slip angles which are attained after a short time of acceleration. Modern airplanes with rounded frames and flowing transitions between the frame and thewiug attain slip angles which are very much higher because of their small keel proportions and accordingly also longer timesof acceleration. r E

This is more particularly true for the maintenance of a correct side inclination during the 'flght in curves; In this case, the side accelerations exert their action in the same manner, that 40 is to say that so long as the airplane is subjected to, a side acceleration,.the ball level cannot be used as an indicating instrument, for it can always remainin the middle in spite of a strong 'slopeerror. It is only in the condition without side acceleration that it can be used again.

. On the other hand, high speed airplanes require in blind fight at least the same and for directional flight even still higher turning speeds than low speed planes. To-day, for a blind flight,

a minimum turning speed of 2 per second is required. In certain cases, turning speeds of 3-4? per second are already required. Now, while a low speed airplane having a speed of 180 kilo meters per hour requires side inclinations of 10- 20 for the required range of turning speeds of 2-4 per second, high speed airplanes with a speed of 360-540 kilometers per hour already require side inclinations of 20-45 for the same turning speed. For these reasons, with high speed airplanes, an exact variation of course is possible 5 only with the control of the corresponding side inclination. If the rudder is actuated alone without the aileron, the airplane will change its course, indeed, but it will flrst maintain the path of its center of gravity until a side inclination to gradually occurs. Then, the airplane swings towards the other side in spite of the straight position of the vertical rudder while maintaining its side inclination and it is subjected to a new side acceleration, so that a coupled oscillation about the vertical and the longitudinal axes occurs. But such a behaviour in turns is not admissible for blind flight and for directional flight.

The invention has for its object to do away. with these disadvantages, and this is obtained by adjoining to the reading indicator of the gyroscopic horizon which indicates the efiective side inclination, a counter-indicator which can be automatically actuated in iunction of a device which determines the intended side inclination. 95

The invention will be described now with reference to the embodiment which is shown by way of example in the drawings. In this embodiment, the invention is applied to a flight surveying instrument the casing of which contains, besides .0

the indicator devices for the longitudinal and the side inclinations, also a turn indicator to the reading pointer of which a counter-pointer, movable in function oi a course indicator, is adjoined.

Figure 1 is a longitudinal sectional view of the flightsurveying instrument.

Figure 21s a front view of the flight surveying instrument. r p 7 z Figure 3 is a plan view of the flight surveying instrument, the casing being partially omitted, and a diagrammatical view of the connections between the measuring mechanisms which are located in the casing. i

In a casing l in which the measuring mechanisms are located, 2 is a rotative magnet system I which transmits to a reading pointer 3 the move ments of rotation imparted to it and eflected by the airplane about its vertical axis. The reading pointer 3 is twice bent'at a right angle and moves with'its free end over a scale disc. 4.- A counterpointer 6 adjacent the reading pointer 3 is movable in function: of a rotative magnet system 5 and'shows the deviations of'the airplane from its prescribed course' It is guided through a double bend at right angles so that it moves with ll its free end over the scale disc 3 and registers with the free end of the reading pointeu i3 and is over this end in the zero position. The pivots of both pointers 3 and 5 are in the. same axis. 1 is also a rotative magnet system moving a. reading pointer 8 according to the movements of the airplane about the transverse axis. Thefree end of the reading pointer 8 is formed as an airplane phantom 9. For the sake of clearness, the reading pointer 8 is shown in the operative position in Figure 1. A rotative magnet system is indicates through a reading pointer ii the move= merits of the airplane about its longitudinal axis. The reading pointer is forked and guided through bends at right angles so that both its free ends move over the scale disc ti and are aligned with the airplane phantom 9 in the zero position. Finally, it is also a rotative magnet system which actuates a reading pointer iii according to the intended side inclinations which are necessary for the flying condition of the moment. This reading pointer is also forked and guided through bends at right angles so that it embraces the reading pointer ii in such a manner that both free ends moving over the scale disc are adjoined to the free ends or the reading pointer it as a counter-pointer. A longitudinal inclination indicator i i, filled with a suitable fluid such as coloured alcohol, surrounds in the form of string the chamber adapted for receiving the inclination indicator or passes through this chamber and is enlarged at 35 in the form of a vessel. The measuring leg of the longitudinal inclination indicator it extends through the chamber between the scale disc 5 and a common sight disc it. Simultaneously; the sight disc it closes the casing 5. For indicating the side inclination, a level it is provided in which a ball 88 can move. The level i? is arranged transversely of the measuring leg of the longitudinal inclination indicator id immediately behind the latter.

In Figure 2, a front view of the flight surveying instrument is shown, the arrangement of the reading pointers and of the measuring instruments themselves being such that it is possible to read all the measured values in thesame visual field. The measuring leg of the fluid inclination indicator it extends transversely of the level it and coincides with the reading pointers 3 and 8 in their zero position. In the zero position, the reading pointer H, the free end of the reading pointer 8 which is formed as an airplane phantom 9 as well as the reading pointer it, are on an ems which is perpendicular to the measuring leg of the fluid inclination indicator ll, preferably about the middle of the same. vided on the scale disc 4 serve to indicate the zero position for the reading pointers 9, II and E3. The fluid charge of the longitudinal inclination indicator ll is preferably calculated so that the level of the fluid in the measuring leg in the zero position is on the horizontal axis of the airplane phantom 9.

The means for actuating and adjusting the rotative magnet systems 2, 5, I, I l and I2 is shown in Figure 3. The rotative magnet system 2 is con-.

trolled by a gyroscopic turn indicatorv 20, which measures in a known manner the turning movements of the airplane about the vertical axis through precession about the axis 2!. A contact arm 22 fast with the axis 2|, and a fixed resistor 23 are bridged with the coil of the rotative magnet system 2. A source of current 2i supplies the necessary energy. During precession, the contact arm 22 slides over the resistor 23. This destroys Marks l9 procontact arm 227, connected with the vertical axis 2%, slides over a resistor 28, thus shifting the coil of the rotative magnet 5 which is bridged with the contact arm 2'8 and the resistor 23 and accordingly also the reading pointer S. The base oi the resistor 28 can be displaced through a worm 2% and a shaft 3%? in function of a course transmitterdi. 82 is a source of current which supplies the bridge system with energy.

The actuation of both rotative magnet systems i and is efiected through an artificial horizon 3d. The latter is formed of a gyroscopic system 85 suspended in a universal joint which is constantly maintained in the horizon through particuiar devices. The gyroscope 35 and its casing are journalled through the axis 3% for rotation in a ring 377 which inits turn is suspended on the hearings is, it by means of the axis 38 which is perpendicular to the axis 3%. Furthermore, the gyroscope 35 is pivotally connected by means of the axis ii which is perpendicular to the axis 3b with a bail 32 provided with a stud d3 engagin a bail 5H3. The latter is suspended for rotation on the bearings td, d? by means of an axis 35) which is perpendicular to the axis 88. The bearlugs 39, #38. 363 and ill are fast with the airplane. 0n the axis 38 or 35, a contact arm it or 69 respectively is provided which slides over a resistor St or 58 respectively. The contact arms 66, 69 respectively and the resistors 59, hi respectively are bridged together with a source of current 52,

' 53 respectively with the coil of the rotative maglibrium or the bridge, which entails a displacemerit of the rotative magnet system I. In a like I dlcation of the amplitude of these movements.

For determining the speed or flight, a wind wheel .58, a so-called air-log, is provided. It comprises a propeller 58 which drives a generator I. through a. shaft 51. The so produced voltage is proportional to the speed. of the propeller and thus gives a. measure for the speed of flight of the airplane. The air-log ofl'ers, with respect to a dynamic pressure gauge which, of course, can also be used, the advantage that its values are independent of the density of the air and, accordingly, true for any altitude. All this is true provided only that the air-log has no work to do, which can be obtained by giving the pro-' peller sufficiently large dimensions, so that the work which is necessary for driving the generator is practically of no importance.

The rotative magnet system H is controlled by means of instrument 54 whereby forces proportional to the rate of turn and the direction of the rate of turn, and the speed of flight are combined to produce a force proportional to the product of said forces. The rotative magnet system [2 is adjusted according to this. product so that the pointer l3 assumes a position dependent upon the product of air speed and rate of turn 01 Du.

nation of the airplaneis readily maintained by the pilot. v

Means for combining the forces proportional to the air speed and rate of turn, respectively, are well known in the art and such well known means may be included within the casing of instrument 54. An example of such means is illustrated in the U. S. patent to E. Fischel, 2,137,974, dated November 22, 1938. Referring to 'Fig. 3 of said patent, electrical means are shown comprising a pair of coils producing a force which is proportional to the product of 1m.

Referring to Fig. 3 of the present application, the leads of the speed responsive device 55 are conducted to the binding posts or terminals and GI and thereby induce in a coil within the instrument 54 an electrical force proportional to the speed, in generically the same'manne'r as disclosed in said Fischel Patent 2,137,974. The leads from the rate ofturn gyro 20 are conducted to the binding posts 52, G3, and 64, and thereby induce in a winding within the instrument 54 an electrical force proportional to the rate of turn and the direction of said turn. These electrical forces are thereby combined and make available at the binding posts 69,10, and H an electrical force proportional to Do: which is applied to the magnet system l2.

While the rate of turn device 20 is suitable for small inclinations of the craft, with increasing inclinations, the indications thereof decrease as a cosine function of the angle of inclination.

The product of air speed and rate of turn therefore, as produced by the device would decrease with increase of inclination. In order to correct this diminution means actuated by the horizon 34 are utilized to modify the combined action of intheartsuchasthose disclosedinFlg.3ofsaid.

FischelPatent 2,187,974 whereby forces propor- By maintaining the pointers II in coin-- cidence with the pointers IS, a correct side incli-' tional to the rate of turn, speed and inclination about the longitudinal axis are combined to therebyproduce a force proportional to as, which is compensated in proportion to the amount of inclination about the longitudinal axis of the craft. The force applied to. the magnet system I2 is thereby varied accordingly. a

With the arrangement according to the invention, it is easy for the pilot to give his airplane a correct side inclination. He has only to maintain the indication of the actual side inclination in coincidence with the indication of the required side inclination and to determine from time to time whether the ball level remains in its middle position for this condition. This gives also the possibility of checking the electrical indication through a mechanical indication for determining whether it is correct or not.

Thus, it results from the foregoing that high speed airplanes can be manually controlled in blind flight in a perfectly satisfactory manner by means of the slight surveying instrument according to the invention. It is also possible, of course, to transmit the values measured by the instrument to an automatic control device. An automatic control device constructed according to this principle can steer and turn a high speed airplane satisfactorily, since every course correction is aided by the required variation of side inclination.

'WhatIclaimiszy 1. An indicating device for aircraft comprising a gyroscope responsive to inclination of the craft about its longitudinal axis, a dial, a pointer carrying two indicators disposed on diametrically opposite sides of the face of. said dial operatively connected to said gyroscope and responsive to motion of said craft about its longitudinal axis, a second pointer carrying two indicators for synchronous movement in a given path substantially parallel to and adjacent the paths of said first two indicators, respectively, and means responsive to the product of factors respectively proportional to the speed of the craft and the rate of turn,- modified by the instantaneous angle of bank for actuating said second pointer and indicators carried thereby.

2. An indicating device for aircraft comprising a gyroscope responsive to inclinations of the craft about its longitudinal axis, a dial, a pointer carrying two indicators disposed on diametrically opposite sides of the face of said dial operatively connected to said gyroscope and responsive to motion about the said longitudinal axis, a second pointer carrying two indicators for synchronous movement in a given path substantially parallel to and adjacent the paths of said first two indicators,

respectively, and means responsive to the product of factors respectively'proportional the speed of the craft and the rate of turn of the craft for actuating said second pointer and the indicators carried thereby.

PAUL nnoaan xbs'rna. 

